Method and device of synchronizing cinematographic performance and sound production



Dec. 23, 1930. J. J. F. STOCK 1,786,368

METHOD AND DEVIGELOF SYNCHRONIZING CINEMATOGRAPHIG PERFORMANCE AND SOUND PRODUCTION I Filed April 23, 1926 2 Sheets-Sheet 1 .52 renar' Jo harm Jacob Friedrich 5+0ck 7 -Dec.

- J. J. F. STOCK 1,786,368

METHOD AND DEVICE OF SYNCHRONIZING GINEMATOGRAPHIC PERFORMANCE AND SOUND PRODUCTION Filed April 23, 1926 2 Sheets-Sheet 2 Patented Dec. 23, 1930 UNITED STATES PATENT OFFICE 4 JOHANN JACOB FRIEDRICH STOCK, OF MUNICH, GERMANY METHOD AND DEVICE OF SYNOHRONIZING OINEMATOGRAPHIC PERFORMANCE AND SOUND PRODUCTION Application filed April 23, 1926, Serial No. 104,197, and in Germany May 4, 1825.

In the usual method of transmitting sound from a central transmitting station as an accompaniment of cinematographic performance, the operators at the various receiving '5 stations are compelled constantly to watch k visible or audible signs, by means of which they are able to run their films in synchronism with a master film at the distant central station. The music, or other audible per- Eormance, is transmitted from thesaid central station either by wire or wireless and it is evident that when, in this way, the films can be made to synchronize, the music will, in turn, synchronize with the films, provided of course, that it synchronizes with the master film.

This known method, depending entirely upon the vigilance of the operators, is both inconvenient and unreliable, and it is the object of this invention to provide a considerably more simplified and yet, under normal conditions, absolutely reliable method of the character mentioned.

With this and other objects in view, the invention mainly consists in obtaining synchronism between sound production and film projection-- First, of the master film in conformity w1th the depending films at the receiving stations by automatic time-bound regulation of the cinematographic picture sequence, and

Second, of the sound production in conformity with the master film by the observance of visible or audible signs at the central transmitting station only or by mechanically synchronizing a sound reproducing machine with the master film at the transmitting station only.

One way of carrying my invention into ef- 40 feet is the following: At the central transmitting station a master film is projected in conformity with the accompanying sound production; the advance of the film through the projecting apparatus-is thereby governed in dependence of the movements-of a clock,

so that each second a definite number of pictures on the film strip or band will pass the lens of the camera, or the projecting apparatus respectively. At the various receiving stations, the films which must be of the same kind are likewise advanced in dependence upon the movements of similar clocks, and so that the number of pictures per second passing through each of the distant apfparatus I will be exactly the same as the master lm. If then, the cinematographic projecting apparatus of the master film at the same time is caused to drive a sound reproducing device, so that synchronism of sound and picture exists at the transmitting station, it is evident that synchronism will also exist between the transmitting station and the receiving station or stations, if the sound so produced be transmitted by wire'or wireless. This will especially be the case when sound and'picture have originally been recorded together. If desired, the master film projector as well as the show film projectors may be automaticallv started at pre-arranged times.

While the manner of synchronizing the advance of the various show films with that of the master film may always be practically the same, namely by some form of time control, the synchronism of the master film with the sound production may be effected in various ways. For example the master film, or an auxiliary film band running in synchronism therewith at the transmitting station, may contain the photograph of a person or of a mechanism, of which the movements are also projected onto the screen, so that the person or persons such as may be employed to produce the sound accompaniment, may take their lead from the projected movements of the said person or device. For example, if a band-master be projected in the act of conducting his band at the same time with the film picture, a band or a choir will at every performance be able to carry on by following the movements of the cinematographed band-master. An an alternative, the auxiliary film may contain the written words for a speaker to repeat, or the music for a musician to play, and so on, so that the person or persons performing the audible part may be guided thereby so as to always keep their actions in synchronism with the projected pictures of the film.

Another way of obtaining synchronism of the master film with the sound production (singing, speech or the like) is to operate a sound reproducing device in conformity with the film, and to transmit the sounds so produced to a person or persons at the transmitting station b means of head telephones so that they may able to repeat what they hear into the microphone at the same moment of reception. ThlS manner of transmission. is

particularly a plicable when speeches are to e transmitte to complement the cinematographic picture of the speaker himself. In this case both the original speech and the photograph of the speaker are recorded together, the former by phonographic, electromagnetic or other sound recording means, and the latter cinematographic. After the films with the cinematographic picture of the speaker have been sent to the various receiving stations, the films are started at an exactly prearranged time and the speech transmitted from the central station in exactly the natural voice of the speaker and in synchronism with the movements, for example the gesticulations of the projected film picture. As'a further alternative the sound reproduced by the sound recording mechanism may be directly transmitted by wire or wireless so that the presence of the speaker or singer himself will not be necessar In order to avoid disturbances it 1s advisable to employ two master films and also duplicate the visual or audible devices used at the central transmitting station.

Recording the pictures is effected in the most simple manner by taking a fixed number of p1cturefor example eighteen in a. unit of time, and. keeping this number constant duringthe whole time of film exposure.

'That is to say, the cinematographic camera must be so operated that it takes exactly eighteen exposures in every second. The sound performance which is to accompany the films is taken up, i. e. recorded, at the same time by some sound recording apparatus in a manner already described.

When the films are to be played after they have been )sent to the. various receiving stations,.the transmitting station first gives a time signal to the operators at all receiving stations a short time before the performance is to begin. By this time signal the operators at the different stations must set thelr clocks so as to be in absolute unison with the master clock at the transmitting station. This having been done the transmitting station an nounces the exact time when the performance will begin, and when this time has arrived all projectors are set in motion either by hand or automatically. In order to compensate for a loss of time which any of the distance operators may have incurred by inadvertence or neglect, the speaker at the transmitting station may begin to read the film title and the introductory words aloud, his words being simultaneously transmitted to the operators 1,7ea,ses

so that they will be able to correct the run of their projectors for example by speeding-up or braking the motors used to advance the film through the apparatus. As in this way the speed of all the projectors is made to correspond, the number of pictures assing the lenses in a given period will also the same and, moreover, will be constant throughout all the performance, being governed by what may be termed a common positive time control. The radio set may then be put into operation either by hand or in known manner by electric contact through the film itself. Interrupting or settin the radio at rest may also be carried out by and or automatically. A great advantage of this arrangement over t e known arrangements resides in the fact that the latter have always depended on two different lengths of wave for transmitting the sound and for sending the synchromzing as on 7 one wave is required with the method according to this invention. The known arrangements .or methods further make censtant watching of signs necessary, which according to this invention is not the case, as the apparatus once started will run satisfactorily right to the end, in view of the fact that the se uence of the pictures is regulated by the mac ines running to exactly the same time. Except at the start, the operators need not trouble about synchronism at all, and should any calls or announcements have to be given from the transmitting station, this can easily be done in an interval between pieces or at the end of the performance.

The new process may be somewhat modified in that during the taking of the photographs, the pictures taken 1n each second may be numbered as by means of some counting or the like mechanism. In the aforementioned example this means that consecutive numbers may be photographed with the film, and that every eighteenth icture, or every set of eighteen for examp e, will receive a new progressive number. In order to make this numbering more easily recognizable it -may be carried out so that the thousands and the hundreds of each figure ap ear at the left hand side,. and the tens an units on the right hand side of the pictures on the film. Instead of numbering the seconds on the film it may be expedient to photograph time-indicatin figures thereon giving the running time directly so that the operators at the various receiving stations need only occasionall compare these time indications with their 0 ocks and correct for any errors by accelerating or retarding the speed of their pro ectors.

As a further modification of the time control afforded by the new method, a seconds clock may be photographed together with the film for the latters extent of the preliminary announcement, or more if desired. In

marks to the receiving stations, wherefrom one end of its stroke to the other.

this case itis advisable to start all the projectors automatically at the same time by causing an electric contact to be made at an exact second, this second being announced by the transmitting station before the commencement of the performance.

A device to carry out the aforesaid method and by means of which the taking and the reproduction of the cinematographic pictures may be regulated accordin to time, is illustrated in the accompanying drawings by way of example. The drawings are largely diagrammatic so as to be more easily understood, three different modifications being shown.

Fig. 1 shows the arrangement of a clock mechanism adapted to serve the purpose of the invention,

Figs. 2 and 3 illustrate electro-magnetic deices to be used in conjunction therewith; an

Fig. 4 is a diagrammatic representation of a cinematograp ic film having a seconds clock photographed thereon, one second being completed whenever a certain number (fifdpictures, sixteen for instance, have been Referring to Fig. 1, the illustrated arrangement of mechanism according to the invention consists of a clockwork which is enclosed in a casing a and having a pendulum b which is provided with a contact spring or the like b adapted to slide over contact segments 0', 0 or c as the pendulum swings s it is most convenient to suspend the device directly from the camera stand, a ball socket or other universal joint :1: is provided so as to prevent the clockwork being affected by inclined positions of the cinematographic apparatus. v

Whereas the movement of the clock may be of any known or convenient type, it will be seen that its face materially differs from the ordinary clock inasmuch as three distinct dials are provided, of which the largest, d, is divided into 100 units of one full second each, while the dials c and f are divided into ten parts each giving the number of hundreds and of thousands of seconds respectively. I

The contact spring of the pendulum 6 moves constantly over one of the contact segments 0', 0 or 0 and thereby causes a variable number of electric contacts to be opened and closed in quick succession, the said contacts being made variable by mounting said contact segments upon a ground plate 9 which, by means of a hand wheel 1' and a rack and pinion arrangement k may be raised and lowered so as to bring either the segment 0, 0 or 0 into the path of the contact spring on'the pendulum. The radius of all the segments is the same, namely the distance from the turning centre of the pendulum to the spring I) which slides over the segments.

As the sequence of the electric contact naturally reverses on the back swing of the pendulum, reversing contacts 1 are arranged at the ends of the pendulum way, which ermit of the same order being maintaine on the back stroke as on the forward stroke. That is to say, whereas normally the numerical order on the back swing would be 4, 3, 2,

1, it will now be 1, 2, 3, 4, exactly the same as on the forward stroke.

From Fig. 1 it will be seen that the segment 0 comprises eight, segment a nine, and segment 0' ten contacts. According to the position of the ground plate g the spring 1; of the pendulum thus moves over eight, nine or ten contacts respectively and thus causes a corresponding number of electric impulses which are utilized to either drive or regulate the advance of the film through the cinematographic apparatus. An index or pointer is provided which shows the number of pietures taken or reproduced per second on the scale over which the pendulum is adapted to move when the position of the ground plate is altered.

The drive of the cinematographic apparatus is preferably continuously applied to the shaft m by means of a hand crank 0, an electric motor or other suitable means. A friction disc n is provided which is moved by the said hand crank 0 and which acts upon a driving pinion p engaging a toothed wheel p on the main shaft m, i. e. the film winding or reeling shaft of the camera. Now, owing to the driving force being continuously applied, it is necessary to interrupt the rotation of the shaft m. each time an electric contact is established by the pendulum b of the clock, during which interruption the friction disc n slips so that the crank 0 turns inefiectively. In order to interrupt the drive every time an electric impulse is sent out by the clock, a ratchet wheel q is mounted upon the main shaft m of the cinematographic apparatus which is in connection with the toothed wheel 1). A double acting pawl r is provided toarrest the ratchet,-and therewith the drive of the ap aratus, the operation being such that the said ratchet is allowed to turn by the amount of one tooth each time the electric circuit is opened or closed. A spring 1" serves to. distract the pawl r from the solenoid s at at the interruption of the circuit, while the closing of the circuit causes the solenoid to attract the respective end of the pawl, like an armature. Any convenient source of electricity may be used; a four-volt battery ar- -ranged for exam le in the lower portion of the casing a has een found to give good results.

When the time regulating arrangement is in operation the pawl 1" becomes attracted eight times every second (or nine or ten shorter.

pendent of the speed at which the crank 0 of the apparatus is rotated, no acceleration and no retardation being possible as ever electric impulse which is sent out by the clock does not allow more than one tooth being shifted at a time; any excessive force applied being inefi'ectively consumed by the friction clutch.

Tn thearrangement according to Fig. 2 the electric impulses are utilized directly to efj feet the transport or winding of the film .through the a paratus. Also in this figure,

the main sha t of the apparatus serving to efi'ect the advance of the film through the camera is denominated by 112.. To this shaft a ratchet wheeht is secured with the teeth of which the hooked armatures u. and u of two mutually opposed electro-magnets o, o are adapted to engage. The electric impulses which are sent out by the clock are led into the magnets 12, 2) by the terminals 1,2, and 3. Thus, at the moment at which an electric contact is made the magnets receive current and alternatingly attract their armatures which, by means of their hooked ends, cause thematchet t to be advanced each time by the amount of one tooth. When the current ceases the armature 11, drops by itself into its position of rest, whereas the armature u of the electromagnet '12 must bereturned by the spring a provided for the purpose.

Every partial rotation of the ratchet for the amount of onetooth causes the advance of one film picture before the lens of the apparatus. Thus, when sixteen impulses are sent from the clock into the electro-magnets, of which every other impulse passes through thesame magnet, it is evident that each of the armatures is attracted eight times in every second which corresponds to the advancement of sixteen film pictures through the apparatus. In this way there is a time of +2 seconds for the stroke of each armature, so that one sixteenth of a second stands at disposal for attractingthe armature, and a further sixteenth for its return, although in practice, these moments are very much With this kind of time control it is advisable to arrange a separate drive for the film reels, which may be independent but operating at the same speed with the advance of the film in front of the lens.

Fig. 3 illustrates a further modification of the film advance controlling means. The cinematographic apparatus is assumed to be driven by an electro-motor or by hand, for example as shown in Fig. 1. The electromagnetic device shown in Fig. 3 is interpositioned between the driving means and the apparatus, and the excitement of the magnets is used to sto the armature, and therewith the picture a Vance, for the duration of a closed circuit interval until the next series of magnets becomes excited, when a turning moment is imparted to the armature and another step in the advanceof the film takes place, and so forth.

The device itself is constructed on the principle of an alternating current motor, the electromagnetic field being composed of sixteen poles of which always four are connected in series as indicated by the Figures 1, 2,3, 4 on the leading-in wires and on the magnet cores. The pole-shoes are arranged in a circle equidistant from each other. Within this circle a four-pole armature w is adapted to rotate so that its four poles are always opposite a series of magnets in the field. The armature shaft m corresponds to the shaft on in Figs. 1 and 2 and serves to drive the apparatus. When the pendulum I) of the control clock swings over the contact segment 0 it causes sixteen opening and sixteen closing impulses. Thus each of the four groups of magnets receives four impulses per second in the order, 1 2 3 4, 1 2 3 4, and so forth, so that the armature is intermittently moved from one pole to the other which intermittent movement, taking place sixteen to twenty times a second, is not discernible to the eye and is almost continuous.

By employing a suitable winding, especially for the armature, the device according to Fig.3 may be used to drive the apparatus by itself. In this case a-four-pole relay will have to be arranged between the control clock and the magnet winding in order to prevent the occurrence of too large sparks at the contact segments of the clock. This arrangement is especially suited for the cinematographic reproduction of films for which a motor is to be used which is provided with, or in connection with the electro-magnetic device just described. This motor will have to be regulated so that the turning moment of the armature w decides the movement of the machine in the required sense.

What I claim is 1. In combination with a (-inematographic camera having a film winding shaft. a device for feeding equal lengths of cinematographic film through the camera during equal intervals of time, comprising a continuous drive for the winding shaft, a friction clutch connected between the said shaft and drive, a pawl and ratchet arrangement on said film winding shaft, an electro-magnet for influencing said pawl, a clockwork mechanism, means associated with said mechanism for causing a definite number of electric impulses per second, and an electric connection between said electric means and the electromagnet causing the armature of the latter toattract and releasev the said pawl under the influence of the electric impulses sent out by the clock mechanism.

2. In combination with a cinematographic apparatus, a device for feeding equal lengths of film through the apparatus during equal intervals of time, comprising a continuous drive for the cinematographic apparatus, a friction clutch interposed between the said drive and the film transporting mechanism of the cinematographic apparatus, a clockwork, means in connection with the said clockwork for causing a definite number of electric impulses per second, and means influenced by the said impulses for temporarily arresting the film transporting mechanism while maintaining the continuous drive of which the surplus amount of force is ineffectively taken up by the said friction clutch.

3. In combination with a cinematographic projector apparatus having film feeding drive means, a device controllin the feed so as to pass equal lengths of 1m through the apparatus during equal intervals of time, comprising a clock mechanism having a swinging pendulum, a contact piece on said pendulum, a plurality of electric contact segments movable selectively in relation to the contact piece on the pendulum and each of said segments having a different number of contacts, an electric circuit including said segments, and a check means in said circuit operable under electric impulses caused by said pendulum passing over the contact segments for momentarily interrupting the feed drive a definite number of times with each swing of the pendulum.

4. In combination with a cinematographic projector apparatus having a driven projector apparatus, a device for controllably feeding equal lengths of film through the apparatus during equal intervals of time, comprisin a clock mechanism having a swinging pendu um, a contact piece on said pendulum, a ground plate, a plurality of electric contact segments mounted on said ground plate and each of said segments having a different number of contacts, means for raising and lowering said ground plate to bring one of the segments into the path of the contact piece of the pendulum, an electric circuit including said segments, and means in said circuit for regulating the advance of the projector apparatus accordin to consecutive current impulses occasione by said pendulum passing over the contacts.

5. Means duplicatively connected with each of a plurality of independently operated cinematographs for feeding predetermined lengths of film therethrough during predetermined intervals of time so as to advance the film through each correspondingly, comprising in combination with each cinematograph, a film feed mechanism, a clocklike device having a swinging contact member, an electric circuit including electric contacts over which the contact member of said device moves to open and close the circuit a predetermined number of times during each second, and means associated with the film feed mechanism and influenced by the open ing and closing of the circuit for alternately slipping and engaging the drive of said film feed mechanism.

6. Means duplicatively connected with each of a plurality of independently operated cinematographs for feeding predetermined lengths of films therethrough during predetermined intervals of time so as to advance the film through each correspondingly, comprising in combination with each cinematograph, a film feed mechanism, a clock-like, mechanism having an oscillating contact member, an electric circuit including electric contacts over which the contact member of said clock mechanism moves to open and close the circuit a predetermined number of times during each second, means operating the film feed mechanism, and means associated with said feed mechanism and connected in circuit with said contacts for limiting the advance of film pictures in a given time according to the number of electric contacts made by the clock mechamsm.

7. The method of synchronizing cinematographic performance and sound production, characterized by automatically regulating the advance of cinematographic film at a transmitting station b positive time-coir trol means, correspondingly regulating the advance of duplicate films at receiving stations operable independentl by like timecontrol means correspondingly set, and regulating thesound reproduction at the transmittlng station to accord with the film ad- Vance therea-t, while simultaneously trans mitting the sound therefrom to the receiving stations.

8. The method of synchronizing cinematographic performance and sound production, characterized by automatically regulating the advance of cinematographic film at a transmitting station by positive time-control means, correspondingly regulating the advance of duplicate films at independently operable stations by like time-control means correspondingly set, and producing and regulating sound accompaniment for the film according to the advance thereof at the transmltting station only while simultaneously transmitting the sound to the receiving stations.

' 9. The method of synchronizing cinematographic performance and sound production at a transmitting station with like performance and sound production at-a number of receiving stations, characterized by advancing the master cinematographic film at at the several receiving stations correspondingly by positive time-control means alike and correspondingly set at all the stations, fixing the performance periods according to the time-control means at the transmitting station, and producing and regulating sound accompaniment for the film according to the advance thereof at the transmitting station only while simultaneously transmitting the sound therefrom forreproduction at the receiving stations.

10. The method of synchronizing cinematographic performance and sound production at a transmitting station with those at a number of receiving stations, characterized by advancing the master cinematographic film at the transmittin station and correspondingly advancing duplicate films at the several receiving stations directly by time control mechanism alike and correspondingly set at all the stations, fixing the periods and beginning moment of performance at all stations according to the control mechanism at the transmitting station and regulating the rate of sound production at the transmitting station to accord with the progressive setured per quence of the projected film pictures thereat, while transmitting the sound therefrom for simultaneous reproduction at the receiving stations.

11. The method of synchronizing cinematographic performance and sound production at a transmitting station with those at a number of receiving stations, characterized by advancing the master cinematographic film at the transmitting station and duplicate films at the several receiving stations correspondingly by direct control of time mechanism substantially alike at all the stations, setting the time mechanisms at the several receiving stations correspondingly with the mechanism at the transmitting station, connecting the cinematograplhic projector at the transmitting station wit a sound reproducing mechanism so that the latter runs in synchronism with the said master film and transmitting the sound produced by the said mechanism at the said transmitting station to the receiving stations.

12. The method of synchronizing cinemat ographic performance and sound production, which consists in automatically regulating the advance of the cinematographic film at a transmitting station by positive time-control mechanism, correspondingly regulating the advance of duplicate films at the receiving stations independently by like mechanisms set correspondingly with the mechanism at the transmitting station, controlling the rate of sound production at'the transmitting station in synchronism with the master film advance thereat so as to make the soundroduction accordvwith the picfgrmance and transmitting the 1,7se,aesi

sound to the various receiving stations for and set correspondingly with that of one of the stations, producing and transmitting. a

sound accompaniment for the film at said one of the stations in accord with the rate of film advance thereat and reproducing the transmitted sound at the other stations with their advance at the same'rate.

14. The method of sychronizing cinematographic performance and sound production at a plurality of stations simultaneously, which consists in regulating, the start and sequence of the film picture projection at each station independently by direct control of clock mechanism alikefor all stations and set correspondingly with that of one of the stations so that all will operate correspondingly, regulating the rate of a related sound production at said one of the stations to accord with the sequence of proection thereat, transmitting said sound therefrom to theother stations and re roducing the sound at said other stations w ile maintaining the projections thereat.

15. In combination with a cinematogra hic apparatus having a driven main sha a device for advancing a definite number of cinematographic pictures through the proector thereof in a given interval of time, comprising a. driving shaft having (associated slip-clutch means for imparting its drive to said main shaft, 9. clock-work-mechamsm, means connected with said mechanism for causin a definite number of electric impulses there om per second, and means intermittently operable by said impulses for momentarily interrupting the main shaft drive a predetermined number of times within a predetermined unit of time.

16. The method of synchronizing cinematographlc performance and sound production at a plurality of stations simultaneously, characterized by starting and advancing duplicate cinematographic films at all stations directly by time control mechanisms alike in each station and set for corresponding operation, producing and transmitt-ing a sound accompaniment for the film at one of the stations in accord with the film advance thereat, and reproducing the trans mitted sound at the other stations where the duplicate films are correspondingly advanced. i

17. In an arrangement for practicing the method of synchronizing cinematographic film projection with sound accompaniment as claimed and described herein, the combination with a cinematograph having mechanism for feeding a film therethrough, of a clock-like device having a movable contact member, contact pieces over which said member is movable, and check-means in circuit with said pieces and operable retardably upon said mechanism by electric impulses through the circuit for controlling the rate of film feed in consonance with the rate at which the sound accompaniment is produced. In testimony whereof I aflix my signature.

T JOH. JAG. FRIEDRICH STUCK. 

